A.O. Smith 100 Series Installation And Operating Manual

25
CALCULATING EQUIVALENT FEET (PDV)
Table 13. Calculating Equivalent Feet (PDV)
Water
Heater
Model
Heater
Input (Btu/
Hr)
Vent Size
(Inside
Diam.)
Pressure Switch Settings
(in. w.c.) 2 Pipe Equiv. Vent Length Conc. Vent Equiv. Vent Length
Intake Exhaust Max. Min. Max. Min.
40 gal. 50,000
2”
-1.88 1.8
60 ft. (18.3 m) +
termination
7 ft. (2.1 m) +
termination
50 ft. (15.2 m) +
termination
7 ft. (2.1 m) + termi-
nation
50 gal. 65,000 -1.88 1.8
40 gal. 50,000
3”
-1.88 1.8
150 ft. (45.7 m) +
termination
10 ft. (3.0 m) +
termination
130 ft. (39.6 m) +
termination
10 ft. (3.0 m) +
termination
50 gal. 65,000 -1.88 1.8
40 gal. 50,000
4”
-1.88 1.8
180 ft. (54.8 m) +
termination
15 ft. (4.6 m) +
termination
N/A N/A
50 gal. 65,000 -1.88 1.8
Notes:
1. A horizontal vent must have a 45° or 90° vent termination elbow to direct the vent pipe downward unless otherwise specied by local requirements.
2. A vertical vent must have a 90° elbow to direct the vent pipe horizontally followed by a vent termination 45° elbow to direct the vent pipe downward unless otherwise
specied by local requirements.
3. If additional elbows are used in the vent system the allowable vent lengths are reduced.
4. Two 45° elbows are considered the equivalent of one 90° elbow.
Table 14. Calculating Low Prole Equivalent Vent Length
Water
Heater
Model
Heater
Input (Btu/
Hr)
Vent Size
(Inside
Diam.)
Pressure Switch Settings
(in. w.c.) Low Prole Equiv. Vent Length
Intake Exhaust Max. Min.
40 gal. 50,000
2”
-1.88 1.8
60 ft. (18.3 m) +
termination
7 ft. (2.1 m) +
termination
50 gal. 65,000 -1.88 1.8
40 gal. 50,000
3”
-1.88 1.8
150 ft. (45.7 m) +
termination
10 ft. (3.0 m) +
termination
50 gal. 65,000 -1.88 1.8
Notes:
1. If additional elbows are used in the vent system the allowable vent lengths are reduced.
2. Two 45° elbows are considered the equivalent of one 90° elbow.
POWER VENT (PV)
It is imperative that the rst hanger (or support) be located on the
horizontal run immediately adjacent to the rst 90° elbow from the
vertical rise. Support method used should isolate the vent pipe
from the oor joists or other structural members to prevent the
transmission of noise and vibration. Do not support, pin, or otherwise
secure the venting system in a way that restricts the normal thermal
expansion and contraction of the chosen venting material.
If the water heater is being installed as a replacement for an existing
power vented heater in pre-existing venting, a thorough inspection of
existing venting system must be performed prior to any installation
work. Verify that correct material, as detailed in this manual, has been
used, and that the minimum or maximum vent lengths and terminal
location as detailed in this manual have been met.

A.O. Smith 100 Series Specifications

General

Brand	A.O. Smith
Series	100 Series
Category	Water Heater
Vent Type	Atmospheric
Type	Tank
Fuel Type	Natural Gas, Propane
Warranty	6-Year Limited Tank and Parts